The increasing of congenital malformations and anomalies today is giving rise to heightened awareness and interest. The diagnostic modalities currently available include chorionic villi sampling (1st trimester), amniocentesis(2nd trimester),
cordocentesis, placenta biopsy(2nd 3rd trimester)and etc. This study aims to demonstrate the effectiveness of chorionic vili sampling, amniocentesis, cordocentesis and placenta biopsy in the prenatal detection of chromosomal anomalies according
to
the
gestational ages of the fetuses, and was conducted from January 1985 to July 1990 at Yonsei University, College of Medicine. Three hundred and sixty-four cases(175 cases of chorionic villi sampling, 170 cases of amniocentesis, 19 cases of
cordocentesis
and placenta biopsy) who had underwent prenatal cytogenetic studies according to their gestational ages were performed. The indications for chorionic villi sampling and amniocentesis were 39.7% and 32.3% for advanced maternal age, 22.8% and 28.8%
for
previous chromosomal abnormality, 20.1% and 21.2% for previous congenital anomaly of the fetus respectively. The indications of cordocentesis and placenta biopsy were 94.7% for suspicious ultrasound findings and 5.3% for late booking or
unsuccessful
amniotic fluid cell culture respectively. Abnormal fetal karyotypes were obtained in 12 cases(3.3%). The cytogenetic results of 5 cases with parental balanced translocation were same as the parental karyotypes in 2 cases, 1 case of partial
tirsomy
and 2
cases 2 cases of Down Syndrome. Fetal loss rates were 5/175(2.9%) in chorionic villi sampling and 1/171 (0.6%) in amniocentesis. Therefore, we hope to make it possible to apply these modalities to high-risk pregnancies regardless of the
gestational
ages
and thus reduce the incidence of congenital anomalies.
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